The amino acid requirements of growing turkeys. 1. Model construction and parameter estimation.

A model has been formulated to calculate the protein and amino acid requirements for growing turkeys. A requirement was taken as the sum of the needs for maintenance, for gain in carcass weight without feathers, and for the feathers. Parameters used in the model were obtained from a study of carcass composition along the growth period and from two balance trials with adult turkeys.

Handling of water and dietary monovalent ions by the young turkey.

Sodium and water turnover rates were measured in young turkeys fed diets with three concentrations of NaCl and kept at 12, 18 or 30 degrees C. Sodium absorption averaged approximately 60% and was unaffected by temperature. Water and sodium pools were affected by temperature and sodium intake.

Cholecalciferol requirements of young turkeys under normal conditions and during recovery from rickets.

Day-old turkeys fed vitamin D-deficient diets became rachitic within 17-24 days. The symptoms included reductions in body weight, plasma calcium and inorganic phosphorus, plasma and intestinal calcium-binding protein (CaBP), plasma 25-hydroxycholecalciferol [25(OH)D3], bone ash, and kidney 25(OH)D3-24-hydroxylase and a rise in kidney 25(OH)D3-1-hydroxylase activity. Supplementation of the diet with 12.

Glucose absorption and starch digestion in the intestine of the chicken.

Starch digestion and glucose absorption were determined in vivo along the chick's (Gallus domesticus) intestine, using 91Y and 51Cr-EDTA as unabsorbed reference substances. About 65% of the ingested starch was digested up to the end of the duodenum, 85% up to the end of the jejunum and about 97% at the terminal ileum. A fraction of about 97% of the glucose, ingested or released from ingested starch, was absorbed.

Phosphate absorption and excretion in the young turkey, as influenced by calcium intake.

Phosphorus absorption in the young turkey, measured with the aid of yttrium-91 as a reference substance, was linear with phosphorus intake. This observation suggested the lack of adaptation of the phosphorus transport mechanism to changes in the phosphorus needs. Phosphorus retention and bone ash initially increased with increased intake to plateau at a dietary phosphorus concentration of about 0.